Commitments and Contingencies - Employment Contracts (Details) - Petrello $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) item
Employment contracts
Employment agreement amount of group life insurance multiplier of base salary \| item	3
Insurance policy amount \| $	$ 5

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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